Two new studies show that microbes found in the mouth may cause colorectal cancer, reports EurekAlert, a publication of the American Association for the Advancement of Science.  Both studies examine a gut microbe called Fusobacteria that is also found in the mouth.  Previous studies have only confirmed that the fusobacteria are also common in tissues from patients with colorectal cancer.  Understanding this source of colorectal cancer can provide medical professionals with another means of treating and preventing colorectal cancer.

These studies, both published in the journal Cell Host & Microbe, demonstrate that fusbacteria can cause colorectal cancer.  The first study, authored by Kostic et al., found that the microbe accelerated the formation of tumors.  The microbe attracted myeloid cells and promoted an inflammatory response.  The second study, authored by Rubinstein et al., found that a molecule on the surface of fusobacteria is what attaches to human colorectal cancer cells.  The molecule turns on the cancer growth genes, stimulates an inflammatory response, and promotes tumor formation.

Colorectal cancer is one that starts in either the colon or the rectum, according to the American Cancer Society.  Most of these types of cancer begin as a growth in the lining of the colon or rectum, known as a polyp.  The majority of polyps do not become cancer, but a subset known as adenomas can become cancer.  If found early, the adenomas or other polyps can be removed before becoming cancerous.  Over 95 percent of colorectal cancers come from adenocarcinomas, which start in the gland cells that line the colon and rectum.

According to the Centers for Disease Control and Prevention (CDC), there were approximately 136,717 people diagnosed with colorectal cancer in 2009.  In the same year, 51,848 people died from colorectal cancer.  Colorectal cancer is the second leading cause of cancer-related deaths in the U.S. It is also the third most common cancer for both men and women.

There are a number of diseases of the colon and rectum, which can have overlapping symptoms, reports the Cleveland Clinic.  Some conditions are functional disorders, where the bowel does not work properly.  Common conditions include constipation and irritable bowel syndrome.  Other conditions are structural in nature, including hemorrhoids, anal fissures (tearing in the lining of the anus), and abscesses.  There are infections local to the area or those that have an impact on the colon and rectum.  Finally, there are disorders of the colon and rectum that can pull in function and structure.  These include diverticular disease, colitis, polyps, and cancer.